This invention relates to steam heating devices, and more particularly, to a closed-system, steam heating unit and furnace. The present invention is an improvement to the structures in my previously issued U.S. Pat. Nos. 3,927,299 and 3,640,546 for STEAM HEATING UNIT and SELF CONTAINED STEAM HEATING UNIT respectively. In counterdistinction to the last noted patented structures, this invention includes a steam heating unit which is particularly adapted for use in combination with a blower unit and heating duct work to form a furnace for central heating systems. To facilitate the increased heat energy required to perform properly in this application, a steam cylinder is provided to evenly distribute the steam to the radiator unit, and to prevent unvaporized liquid from entering the risers. Further, a single vessel boiler unit having an elongate, immersion type electric loop element is provided to supply sufficient steam to the radiator unit. Unlike my previously patented devices, which, under full load operation attained pressures in the nature of 18 to 20 psig, the present unit operates at a pressure just slightly greater than atmospheric, in the nature of 0-3 psig for safe and efficient operation.
The principal objects of the present invention are: to provide a steam heating unit for central heating furnaces; and to provide such a device having a steam tube for evenly distributing steam to the radiators, and preventing unvaporized liquid from entering the same. Other objects of the invention are to provide such a device having a single vessel boiler with an immersion type electric loop element mounted therein; to provide such a device having a tubular return member connecting each lower manifold with the boiler to return condensed vapors thereto; and to provide such a device wherein the tubular return is inclined downwardly whereby the condensed vapors are transmitted by gravitational forces. Further objects of the invention are to provide such a device which is evacuated to a sub-atmospheric pressure and operates at a pressure substantially equal to that of the atmosphere for economical heating; and to provide such a device having an enlarged upper manifold for effectively condensing spent steam. Further objects are to provide such a device having boiler temperature and pressure sensing mechanisms for safely controlling furnace operations; and to provide such a device which is economical to manufacture, efficient in use, capable of a long operating life, and particularly well adapted for the proposed use.
Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention.